Preliminary Study On Chemical Communications Between Maize Infected By Exserohilum Turcicum And Neighboring Uninfected Maize

Last century,with rapid development of chemical industry,chemical products -chemical fertilizers and pesticides were extensively used in agriculture,traditional methods of prevention and control on diseases and insectpests were completely changed.Chemical fertilizers and pesticides raised food production substantially, brought economic benefits,at the same time,ecological environment problems were caused,for example, soil fertility fell sharply;soil was hardened,impervious and degradated;natural ecosystem,biodiversity was destroyed.Environment had also been polluted by poisonous and harmful substance,which had threated people health seriously.Only implementing agricultural sustainable development.On the premise of effective control of insect pests and plant diseases,not only ecological environment was unaffected,but also agricultural productions were increased.The maize was one of important food crops in our country.Exserohilum turcicum was common maize disease.Widespread onset of the disease,maize production went down and maize quality was lowered.In serious year,reduction in maize production was up to 50%.Prevention and control with pesticides showed some detriments,so seeking a new way to settle disease problems was done.Attacking with an outside invasion made plants to emit damage-induced volatiles, which served as interplant alarming signal,induced other plants to prepare for indirect and direct defenses.Under injured conditions,the reports about surrounding plants physiology influences of chemical defence were not detailed.In the controlled conditions,effects on unheathy and surrounding heathy plants of Exserohilum turcicum infection were studied.The research purpose was to provide scientific basis for further improvement on the maize production and quality,by making use of defense system and enhancing the resistance to diseases.Firstly,whether chemical communication existed between infected and healthy plants and whether crops own chemical defence improved disease resistance were explored.Maize seedling was treated with cultural filtrates,spores and clear water three different treatments,and physical changes of infected and healthy plants were determined.Research results showed,proline content,peroxidase activity,catalase activity and superoxide dismutase activity of maize seedlings of treatment groups at cultural filtrates treatment were higher than other treatments.Due to pathogenic bacteria infection,volatile substance was released as signals,which inducted neighboring seedlings to operate warning mechanism.Proline content,peroxidase activity,catalase activity and superoxide dismutase activity of healthy seedlings of inducted group at cultural filtrates treatment were higher than at clear water treatment.There was chemical communication between infected and healthy plants.Using maize own disease-resistance system improved disease resistance for response to the coming adversity stress.Secondly,continuous induction time of infected plants which responted to healthy plants and whether made further improvement on disease resistance with volatiles concentration were explored.Maize seedlings were infected with Exserohilum turcicum and treated group and inducted group maize seedlings were collected in this paper,after that physiology changes of two groups maize on Exserohilum turcicum infection at different time and induced defences between two groups maize were determined.The results showed that with increase in infection time,the injured was intensified.Lipid peroxidation were enhanced along with malondialdehyde content.Proline content was increased,peroxidase activity,catalase activity and superoxide dismutase activity were improved to remove disadvantage influences.Volatile substances were produced from treated group maize seedlings, which were signals to induced group to operate warning mechanism.With signal substances accumulation,proline content was increased,peroxidase activity,catalase activity and superoxide dismutase activity were improved within a given period to improve disease resistance.Perhaps,physiological indexes had a optimum concentration of signals.At this concentration, content or enzyme activity was higher,or enzyme activity had been improved rapidly.Volatiles concentration had certain influence on disease resistance.In general,volatiles released from infected plants were increased with time.Perhaps,disease resistance of maize was improved at certain concentration of volatiles.Thirdly,effects of different culture patterns on healthy seedlings of neighboring maize were studied.Treated maize seedlings were infected with Exserohilum turcicum, monocropping,maize-soybean intercroppingâ… and intercroppingâ…¡were applied in induced group maize in this paper.Physiology changes of healthy maize were determined.The results showed that malondialdehyde content of healthy seedlings of neighboring maize seedlings in monocropping was higher,proline content of healthy seedlings of neighboring maize in intercroppingâ…¡was higher than in monocropping and intercroppingâ… ,catalase activity and superoxide dismutase activity of healthy seedlings of neighboring maize in intercroppingâ… andâ…¡were higher than in monocropping.Volatile substances were produced from treated group maize seedlings,as a signal conducted to induction.Monocropping,maize-soybean intercroppingâ… and intercroppingâ…¡,different culture patterns had different effects on induced resistance.Maize intercropping was more effective than monocropping in protecting plants from coming disease.Perhaps,chemical communication between maize and soybean root systems was against Pro production,enzymes activities were improved with chemical communication between infected maize and intercropping maize.The disease-resistance was improved by agricultural cultivaion measures and maize defense mechanisms which were induced by chemical communication.